Intraocular lenses have gained wide acceptance in replacement of human crystalline lens after a variety of cataract removal procedures. The human crystalline lens is generally recognized to be a transparent structure having a thickness of about 5 millimeters and diameter of about 9 millimeters. The lens is suspended behind the iris by zonular fibers which connect the lens to the ciliary body. A lens capsule surrounds the lens, the front portion of the capsule being commonly known as the anterior capsule and the back portion commonly known as the posterior capsule.
Numerous procedures for the removal of cataracts have been developed in which the lens is removed from the eye and replaced by an artificial lens implant. The extraction procedure may be generally categorized as intracapsular (in which the lens is removed together with the lens capsule) or extracapsular (in which the anterior capsule is removed with the lens, and the posterior capsule is left intact).
Since Ridley implanted the first artificial lens in about 1949, the problems associated with cataract extraction and lens implantation have received a great deal of attention from ophthalmic surgeons.
Various types of artificial lenses have been proposed, and appropriate surgical procedures have been developed which strive to reduce patient discomfort and reduce post-operative complications. Reference is made in this connection to Pseudophakos by N. Jaffe, et al; "History of Intraocular Implants" by D. P. Choyce (Annals of Ophthalmology, Oct. 1973); U.S. Pat. No. 3,991,426 issued to Flom on Nov. 16, 1976; and U.S. Pat. No. 4,092,743 issued to Kelman on Nov. 8, 1977 which disclosures are hereby incorporated by this reference.
Of particular interest in the context of the present invention is the development of surgical techniques requiring relatively small incisions in the ocular tissue for the removal of cataracts as disclosed in U.S. Pat. Nos. 4,002,169 and 3,996,935. A number of skilled artisans have disclosed intraocular lens structures comprising an optical zone portion generally made of rigid materials such as glass or plastics suitable for optical use.
However, one of the principle disadvantages of the conventional rigid intraocular lens is that implantation of the lens requires a relatively large incision in the ocular tissue. This type of surgical procedure leads to a relatively high complication rate, among other disadvantages. For instance, the serious dangers associated with implantation of a rigid lens structure include increased risks of infection, retinal detachment, and laceration of the ocular tissues, particularly with respect to the pupil.
Accordingly, those skilled in the art have recognized a significant need for an intraocular lens implant which affords the clinical advantages of using relatively small incision techniques, yet possesses an optical zone portion having a fixed focal length and which will retain a prescribed configuration once, implanted in the central optical area, thereby providing a safer and more convenient surgical procedure and comfortable fit for the eye. The present invention fulfills these needs.